Process for decolorizing oils



Dec. 25, 1934.

s. E CAMPBELL PROCESS FOR DECOLORIZING OILS Filed Dec. 2, 1932 EKHHMSTEO SETTL/NG 49 Dar/1.40m Z5 ATTQQNQV Patented Dec. 25, 1934 I UNITED STATES PATENT OFFICE c U I r 1,985,717

rnoouss son DECOLORIZING OILS Sumner E. Campbell, Long Beach, Calif. Application December 2, 1932, serial No. 645,402

' '8 Claims. (01. 196-40) This invention relates to a process for decolorizing oils and is particularly applicable to distillates derived from crude oils'in the refining thereof, such crude oils in general including pe- 5 troleum, shale oil, coal tar, and the like.

The principal object of the invention is to provide a simple, highly economical process for refining petroleum distillates to decolorize the same.

A further object is to provide a process wherein a continuous stream flow of petroleum distillates is decolorized and stabilized as to color.

"A further object is to provide a processwherein the color forming compounds and other impurities in petroleum distillates are removed by a continuous process and in such form thatthey may be recovered as by-products of value.

A further object is toprovide a process wherein the gasoline fraction from "crude oil is decolorized to+ on the Saybolt'colorimeter.

In the distillation of crude oil'to produce refinable fractions therefrom applicable to particular uses, it is necessary'to market certain fractions, such as gasoline, kerosene, and the like with no perceptible color therein. i

In general, the closer such color is to water white, the more marketable are such fractions, but whereas water white distillates carry 21+ on the Saybolt calorimeter, bythis process the color can not "only becarried to 30+,b'ut will be stabilizedfl "I'heremoval of color forming compoundsadditionally removes other objectionable compounds in the distillatesuch asgum formingmaterial in gasolines detrimental to its use in many arts.

Heretofore, the high" color (30+) of such fractions has been obtained by a. liberal use of alternating treatments oi large quantities of strong sulphuric acid and caustic soda, the color forming compounds being'drawn oil in'an 'acid sludge which, in the acid treatment, may contain 80% of the original acid and which 80% is lost or difiicultly recoverable. r

In additiomthe reaction productsof such acid treatment contained in' the acid sludge arelikewise lost.

By my process not only is the amount of acid used cut to" a minimum, but I am enabled to use a dilute acid in the vicinity of 50% HzSOiahd can utilize the same until its reaction properties with color forming compounds is exhausted, but I, do not limit myself to theuse of 50 H2504, as other sulphuric acid having'a strength less than 93.19%, or 66 B. maybe used and such'will be referred to herein as fdilute acid". Intact,

almost any dilute acid is effective, sulphuric, acid being generally used on account of its low cost.

Furthermore, the same minimum quantities of alkali, such as caustic soda, may be utilized in similar manner. i

The chemical structure of gasoline varies considerably and this process will beparticularly described by its effect on a gasoline containing color forming compounds, such as nitrogenous and other bases, and also impurities of an acid nature such asphenolsor naphthenic acids, inasmuch as it is highly desirable to not only produce a finished gasoline without color, but also one which will remain colorless or stabilized on continued exposure to light.

:I do not, however, limit myself to the treatment of gasolines inasmuch as other distillates, such as kerosene and aromatics, are susceptible to the action of my process. W

It is believed that the presence of nitrogenous bases in petroleum distillates, particularly gasolines,- is responsible .for the development ofa pink color which usually changes toyellow. on exposure to light. i i 1 It is a further object of this invention to remove and recover such nitrogenous bases.

My process includes selectively removing the nitrogenousj'and other basic impurities and compounds of an acid nature from a gasoline. F

a The selective removal of impurities of a basic nature is accomplished;bycontacting the unrefined gasoline distillate with a relatively dilute acid solution of such strength, say 50% sulphuric acid, so as to absorb, or react,'with the basic compounds, or to form sulphates thereof without material polymerization, to the end that the acid is completely used up in such reactions and the nitrogenous bases may then be recovered from such exhausted acid for uses in various arts. v Itwill be especially appreciated thatthe process is not one of neutralization, but a process wherein the acid used becomes exhausted by reaction with basic compounds, of impurities; whereby the same areextracted from the oil and further while such reactions are being carried on the acid and reaction products are held segregated to the end that no free mineral acid is carried over to the alkali towers wherein acidic impurities are extracted in like manner.

Such procedure is necessary because, if free mineral acid comes in" contact with an alkaline The drawing serves to illustrate, by means of suitable apparatus, one way of applying my proc ess, in which the raw distillate, such as gasoline, is continuously supplied through a pipe 10 and valve 26 to the first treatment chamber or tower 11 of a plurality of such towers 11.

Inasmuch as all the towers 11 are of like construction andproduce like effects in succession, the description and function of one tower is applicable to all.

Tower 11 is filled with any suitable inert acid resistant material 12 to give large surface contact of gasoline with acid, and is partly filled to the line X-X with sulphuric acid .of about 50% strength, introduced through the pipe 13; "said level X--X being merely indicative of .alevel for acid to allow a space .for expansion there,- above of the acid and reaction products extracted by the acid so that no acidjis carried over from tower to tower.

The gasoline is intimately contacted with the acid by flowing therethrough and passes successively through valve 27, pipe 14, valve 28, tower 11', valve 27, pipe 1 f, valve 28, tower 11", valve 27', pipe 14", valve 28", tower 11", valve 27", to a pipe 15, by which it is conveyed to alkali towers through a valve 34 for further treatment with alkali, as will be presently described, valves26', 26", 26, 29, 29 29", 29", 30, 30, 230", 30", 31, 31', 31", and 33 being closed.

, In this manner a continuous stream'of gasoline is contacted with successive relatively small portions of dilute acid, the first of which is first partially spent, or exhausted, by reaction with the basic compounds, and the last of which-is substantially fresh so that, by thus successively contacting, the removal of compounds of a basic nature by: reaction .is assured, with no resulting waste of unrecoverable acid. I

-The course of such treatments the dilute acid in the first tower 11, by reaction with basic compounds, will become substantially completely used up, or exhausted, whereupon valves 26, 27, and 28 are closed and valve 26' is opened to prevent the passage of gasoline through tower l1, whereafter valve: 29'is opened to drain tower 11 of the exhausted acid together with the absorbed nitrogenous bases into a manifold 38 which conveys the same to a storage-tank 89 for further desired treatment.

As soon as thegexhausted acid is withdrawn from the first tower 11, valve 29 is closed and valve 37 opened tofill tower, 11 with fresh dilute acid through pipe 13 to the level XX, after which valve'37 is closed and tower 11 becomes ready for use as'the last in the series instead'of the first.

Pipe 15 is divided at a'v'alve 34 to maintain the plurality of towers 11 in operation in rotation,

which is accomplished-afterthe'withdrawal of exhausted acidfrom the first tower 11, and the replenishing thereof with'fresh dilute acid, by closing'valve 34 and opening a valve 33 in a bypass'manifold pipe 32 adapted to selectively. and in rotation pass the gasoline through the plurality of towers by means of suitable pipes 36, 36, 36", and 36", controlled by valves 30, 30, 30",and 30" respectively.

At the same time that by-pass manifold 32 is opened, a withdrawal by-pass manifold 35, connected to suitable extensions of pipes 14, 14, and 14", through valves 31, 31, and 31" respectively, will be'opened through one or the other of said valves to maintain the flow of the acid treated gasoline back to pipe 15 and further alkali treatment.

Referring back to first tower 11, which had just been recharged with fresh dilute acid, valve 34 is now closed and valves 33, 30, 27, and 31 are opened, whereby the gasoline from tower 11" passes back through tower 11 and thence through pipe 14 and manifold to pipe 15, tower 11' becoming the first of the series and tower 11 the last.

Upon further continuous operation and upon exhaustion of the acid in tower 11, valves 26', 2'7 and 28 are closed and valve 26" is opened, to the end that tower 11 is drained and recharged, by manipulation of the proper valves, with fresh dilute acid as already described, whereupon valve 31 is closed and valves 28, 27' and 31 are opened, to thus make tower 11" the first in the series and tower 11' thelast in the series.

In like manner any number of dilute acid towers can be operated in rotation in order that the greatest efficiency may be obtained from the smallest possible amount of acid employed, substantially no free acid being drawn off from the respective towers to the mixture in storage 39.

This is a great contrast to the usual acid treatments for decolorizing where up to 80% of free acid is often withdrawn in the acid sludge.

In order that no mineral acid or reaction products which it may contain may be carried over to the alkali towers which are used in the next step of my process, pipe 15 carries the acid treated gasoline to a settling chamber 16, whence any accumulated mineral acid or acid liquor may be withdrawn through a pipe 14. This settling chamber is installed solely for safety so that if, due to faulty operation, traces of mineral acid or reaction products are carried over with the gasoline from thelast of the series of acid towers, the acid must be prevented from getting into the alkali towers becauseif any amount of mineral acid comes in contact with the partially spent alkaline solution there are reactions which liberate the impurities already removed from the distillate, and as these liberated impurities are then soluble in the oil it is exceedingly difficult, if not impossible to economically secure a finished gasoline of 30+ oolor Saybolt, and color stable.

In my process mineral acid such as a solution of sulphuric acid containing in the neighborhood of 50% H2s04 has a definite and specific purpose, namely to combine with and remove nitrogenous basic compounds. Also an alkaline solution is employed in my process solely for the purpose of combining with and removing organic acidic impurities such as organic acids and phenolic compounds. An alkaline solution is not used for the purpose of neutralizing mineral acid although it will do soshould faulty operation cause mineral acid reaction products to be introduced into the alkali towers, but such introduction of mineral acid will defeat the object of my process largely.

The gasoline now passes through pipe 18 and valve 40 to a tower 19, which is constructed in like manner to acid tower 12 containing contact material and is partially filled with an alkaline solution, for example a solution of caustic soda, to the level of Y-Y.

In using a relatively strong solution of caustic soda in tower 19, for instance a solution containing 30% of sodium hydroxide, I have found that'such solution absorbs the acidic impurities in the acid treated gasoline with avidity, to the end that the solution absorbs about an equal volume of acidic impurities, or more, depending on the nature of the hydrocarbon material treated, beforebecoming exhausted.

concentrated therein 1 in.

While I do not limitmyself to the use of a 30% .solution of sodium hydroxide, or equivalent soluhydroxide in tower 19 will be less frequent.

However, for convenience, I provide for the use of two or more towers 19 and 19 in series, primarily to maintain continuousoperation, and secondly in case a plurality of towers is necessary when dilute caustic soda solutions are used. -In the latter case, a plurality of caustic soda towers can be arranged-for use in rotation, as already described for the dilute acid towers.

Valve 43 is closed and the gasoline is passed through the caustic soda solution in tower 19 and passes out through valve41, pipe 21, and

valve 40 to a second caustic sodatower 19',

thence through valve 41' and pipe42 to a settling tank 22, wherein any caustic soda solution carried over is settled out and withdrawn through pipe 43, and the treated gasoline then passes through a filter 24 to storage, or use, by means ofapipe25. i

The treatment in towers 19 and 19' insures the removal of acidic impurities in the acid treated gasoline, and after a predetermined period of operation the caustic soda solution in tower 19 becomes exhausted, due to reaction with such acidic compounds. 1

Upon exhaustion of the caustic soda solution in tower 19, valves 40 and 41 are closedand valve 43 opened, to the end that the treatment continues in tower 19, which thus becomes the first of a desired series instead of the last.

Valve 44 is then openedand the exhausted caustic soda solution and reaction products from tower 19 are drainedthrough' a pipe 45 to a storage tank 46, wherein they may be held for further treatment elsewhere for therecovery of valuable acidic materials and withdrawn through pipe 47. i e

Valve 44 is then closedandvalve 48 opened. to partially fill tower 19 with fresh caustic solution supplied by a feed pipe 20,'aft er which valve 48 is closed.

Tower 19 is thus charged and ready for further operation upon exhaustion of 'tower .19,

when valves 43, 40 and 41"will be closed, and: valves 40, 41 anda valve 49 in a by-pass line 50 i will be opened.

Or, as already stated,'a plurality of alkali towers can be arranged in series as provided for the dilute acid towers.

I have found that the acidic impurities usually present are of two classes, namely organic acids and phenols. Both of these classes of impurity can be removed together by a solution of caustic alkali, such as for example a caustic soda solution. However, in some cases I have found it desirable to separate these two classes by first passing the distillate through a carbonate solution such as sodium or potassium carbonate with which the organic acids react to form soaps but i which have no effect on. phenols. I then pass the distillate through towers containing caustic alkali solution when the phenolic compounds unite with thecaustic alkali chemically to form phenates.

Acidification of the soap solution and/or the phenate solution liberates the free organic acids orphenols as the case may be, for any desired purpose.

By the above described continuous treating op.- I

eration, it will be seen that decolorization of distillates may be effected selectively, first in removing impurities of a basic nature which may be recovered as valuable icy-products, and then removing impurities of an acid nature which may be recovered as valuable byproducts, the re- ,moval of both classes of impurities being accomplished byv the use of minimum quantities of acid and alkali, which are used to exhaustion.

In addition, after said treatments, there may still be inthe gasoline certainchromogenic and other bodies unaffected by such treatments, which cause the gasoline to appear turbid and lack brilliancy, and these bodies are, removed (if present) by the filter 24, which contains an adsorbent material, such as fullers earth, and which serves to materially brighten and clarify thegasoline, thereby giving it the brilliant appearance so highly-desired.

Likewise, the steps of my process, prior to filtering throughthe adsorbent material. insure a prolongation of the functionsof the adsorbent material to an extent heretofore unknown, and in, consequence the adsorbent material is easily reactivated by burning, or otherwise.

The nitrogenous bases and other basic impurities removed by the dilute acid treatment collected in tank 39 may be recovered by a treatment such as is described in United States Patent No. 1,686,136, it. being especially noted that the strength of the dilute acid employed is such as to convert the basic compounds intosulphates without material polymerization, or without reacting materially on acidic impurities to change, or possbly destroy, such as are desired to be CO1? lected in the alkali treatment for recovery as products of value.

To this end, the strength of the acid may be varied within rather large limits, depending on the chemical structure of the distillate treated, to obtain results and products unattainable in the use of strong acid in like quantities, in the same steps.

The acidic impurities removed by the alkali treatment and collected in tank 46 include such compounds as phenols, cresols, and the like, and organic or naphthenic acids and the like, which may be recovered in various ways.

The system of rotation employed is such that the gasoline is primarily contacted with apartially'spent dilute acid solution and finally contacted with afresh dilute acid solution,.the.final acidin anyone period of rotation absorbing practically no impurities.

This is necessary in my process, which is primarily for decolorizing the gasoline, because if even a limited amount of impurities remain in the gasoline after the dilute acid treatment, a stable decolorization is not efiected, and such is one of the prime objects of my invention; to produce a gasoline having a 30+ color on the Saybolt colorimeter, which color is stabilized.

However, it must be emphasized that the order of subjecting the oil to acid and alkali treatments is immaterial inasmuch as neutralization is not involved and therefore acidic impurities can be removed by giving the oil an alkali treatment prior to the treatment with acid to remove the basic impurities provided that in either case the treating agent is used to exhaustion before contact with a second treating agent so that impurities, once'selectively removed from the oil, will not be released by any neutralizing effect.

This application is a continuation in part of my copending application Serial No. 349,606, filed March 25, 1929.

a I claim as my invention:

1. In a process of decolorizing hydrocarbon distillates in a plurality of chambers containing contact material and containing sulphuric acid placed in the lower part thereof, the steps which comprise: passing the hydrocarbon distillate upv ward through said chambers arranged in series relation, continuing the passage of distillate until the acid is substantially exhausted in successive individual portions, removing the acid and reaction products in successive individual portions, and maintaining a plurality of the chambers in operation.

2. In a process of decolorizing hydrocarbon distillates in a plurality of chambers containing contact material and containing dilute sulphuric acid placed in the lower part thereof, the steps which comprise: passing the hydrocarbon distillate upward through said chambers arranged in series relation, continuing the passage of distillate until the acid is substantially exhausted in successive individual portions, removing the acid and reaction products in successive individual portions, and maintaining a plurality of the chambers in operation;

3. In a process of decolorizing hydrocarbon gasoline distillates in a plurality of chambers containing contact material and containing sulphuric acid placed in the'lower part thereof, the

steps which comprise: passing gasoline upward through said chambers arranged in series relation, continuing the passage of gasoline until the acid is substantially exhausted in successive individual portions, removing the acid and reaction products in successive individual portions, and maintaining a plurality of the chambers in operation.

4. In a process of decolorizing hydrocarbon distillates in a pluralityof chambers containing con- ,tact material and containing sulphuric acid placed in the lower part thereof, the steps which comprise: passing the hydrocarbon distillate upward through said chambers arranged in series relation, continuing the passage of distillate until the acid is substantially exhausted in successive individual portions, removing the acid and reaction products in successive individual portions, and maintaining a plurality of the chambers in operation in rotation.

5. In a process of decolorizing hydrocarbon dis-' tillates in a plurality of chambers containing con-' tact material and containing sulphuric acid placed in the lower part thereof, the steps which comprise: passing the hydrocarbon distillate upwardly through said chambers arranged in series relation, the first chamber containing partially spent acid and the last chamber containing substantially fresh acid, continuing the passage of distillate until the acid inthe first chamber is substantially exhausted, removing the exhausted acid and replacing the same with fresh acid, and maintaining the chambers in operation whereby said fresh filled first chamber now becomesthe last chamber in the series.

6. A process of decolorizing hydrocarbon distillates which comprises: selectively removing basic and acidic impurities therefrom by continuously passing the distillate upwardly through a series of chambers containing sulphuric acid and contact materialwhereby the basic impurities are removed, then passing the distillate free of mineral acid through an alkaline solution whereby the acidic impurities are removed, the series of acid chambers being so arranged as to exhaust the acid in each successively while maintaining a plurality of the chambers in operation to contact the distillate primarily with nearly exhausted acid and finally with substantially fresh acid.

7. A process of decolorizing hydrocarbon distillates which comprises: selectively removing basic and acidic impurities therefrom by continuously passing the distillate upwardly through a series of chambers containing sulphuric acid and contact material whereby the basic impurities are removed, then passing the distillate free of mineral acid through an alkaline solution whereby the acidic impurities are removed, and finally through an adsorbent material; the series of acid chambers being so arranged as to exhaust the acid in each successively while maintaining a plurality of the chambers in operation to contact the distillate primarily-with nearly exhausted acid and finally with substantially fresh acid.

. 8. A process of decolorizing hydrocarbon distillates which comprises: selectively removing basic and acidic impurities therefrom by continuously passing the distillate upwardly through a series of chambers containing dilute sulphuric acid andcontact material whereby the basic impurities are removed without material polymerization, then passing the distillate free of mineral acid through an. alkaline solution whereby the acidic impurities are removed, the series of acid chambers being so arranged as to exhaust the acid in each successively while maintaining a plurality of the chambers in operation to contact the distillate primarily with nearly exhausted acid and finally with substantially fresh acid.

' SUMNER E. CAMPBELL. 

